1. Field of the Invention
This invention relates to a color light-sensitive material and a process for the formation of a dye image by use of the color light-sensitive material. More particularly it is concerned with a color light-sensitive material which contains a compound capable of releasing a diffusible dye (or dye precursor) by redox reaction (hereinafter referred to as "DRR compound"), and a process for forming a dye image by using the color light-sensitive material.
2. Description of the Prior Art
Japanese Patent Application (OPI) No. 33826/73 (the term "OPI" as used herein refers to a "published unexamined Japanese patent application") discloses a color diffusion transfer dye image-forming method utilizing a DRR compound. DRR compounds as referred to herein are p-sulfonamidophenols or p-sulfonamidonaphthols wherein the dye portion and the nondiffusing phenol or naphthol portion are bound at the p-position through the sulfonamido group. On exposing such a compound in the presence of a light-sensitive silver halide emulsion and then developing the emulsion, the compound is oxidized corresponding to the amount of silver halide developed. This oxidized product decomposes by the action of an alkali processing liquid into a diffusible dye portion containing a sulfonamide group and a nondiffusing benzoquinone or naphthoquinone. It is further described that the diffusible dye so formed is transferred to an image-receiving layer.
However, the inventors' experiments have revealed that the p-sulfonamidophenol as described above fails to provide a transfer density as high as is desirable. Furthermore, the p-sulfonamidophenol, even if it is subjected to a desilvering processing after the release of dye, leaves p-naphthoquinone in a light-sensitive layer, forming yellow stains therein and therefore color images remaining in the light-sensitive layer cannot be utilized as a negative or positive image.
Japanese Patent Application (OPI) No. 113624/76 discloses a DRR compound, viz., an o-sulfonamidophenol substituted by an alkoxyl group at the 4-position. While this compound is very superior in capabilities to conventional, it has been desired to further improve dye-releasing capability.
Additionally, in Japanese Patent Application (OPI) No. 149328/78, a DRR compound comprising o-sulfonamidophenol having an alkoxyl group at the 3-position and a methyl group at the 4-position is described. With respect to this compound also, it has been desired to further improve the dye-releasing capability.
Examples of magenta DRR compounds are described in Japanese Patent Application (OPI) Nos. 115528/75, 114424/74, U.S. Patents 3,932,380, 3,931,144, etc. However, the use of such magenta DRR compounds give rise to the technical problem that the transferred image lacks the desired stability, for example, (1) the light-resistance is insufficient, (2) the fading of color images even when stored in a dark place ("dark fading") is undesirably great, (3) the hue of the color image is easy to change with pH, and (4) the dye portion is insufficiently transferred.
With regard to the dark fading of a transferred color image, for example, it is known in the art that where polymer acids as described in U.S. Pat. No. 3,362,819 (e.g., polyacrylic acid, a copolymer of acrylic acid and butyl acrylate, etc.) are used in a neutralizing layer, the remaining monomers (e.g., acrylic acid, butyl acrylate, etc.) accelerate the dark fading of transferred color images. Subsequent studies have revealed that among such residual monomers, butyl acrylate monomer, in particular, greatly accelerates the dark fading of the magenta image obtained by the prior art method, as described, for example, in U.S. Pat. No. 3,932,380.
However, in producing such polymer acids for use in the neutralizing layer, it is technically very difficult to reduce or remove the residual monomers to such an extent that they exert no influence on the fastness of images. Therefore, it has been desired to develop DRR compounds capable of releasing dye compounds which substantially do not react with such monomers.